Calling device



. s. PETERSON 2,068,700

CALLING DEVICE Filed July 11, 1935 FlG., 2-' PIC-3.3

INVENTOR. SETH PETERSON A TTORNEY.

Patented Jan. .26, 1937 CALLING DEVICE l Seth Peterson, Chicago, 111., assignor, by mesne assignments, to Associated Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application July 11, 1935, Serial No. 30,799

6 Claims.

The present invention relates in general to calling devices, such as are used in automatic telephone systems, and the object of the invention is to reduce the noise produced by the operation of.a calling device of this character.

A calling device which is in wide use is shown in U. S. patent to Obergfell, No. 1,642,822, granted September 20, 1927. This calling device has a finger dial which is variably rotatable in accordance with the different digits. Attached to the dial is a member carrying a pawl, and with the pawl there is associated a ratchet wheel.

When the dial is rotated the pawl is rotated over successive ratchet teeth, the number passed depending on the digit dialled. When the dial is released it is returned by means of a spring at a constant speed controlled by a governor. On the beginning of the return movement the pawl engages the then adjacent ratchet tooth and rotates the ratchet wheel while the dial is returning. The ratchet wheel has an associated, gear wheel which drives the impulse sending mechanism.

When the dial of a calling device of the fore- 5 going character is rotated in accordance with a digit, the pawl passes over a number of ratchet teeth, as stated, and being controlled by a spring it drops into the notches between successive teeth with a clicking noise which is quite noticeable especially if the dial is rotated rapidly. This clicklng noise is more or less objectionable, and the object of the invention, more specifically, is to eliminate this particular source of noise.

The invention will be described hereinafter in 5 connection with the accompanying drawing, in which Fig. l is a front view of a calling device with finger dial removed, Fig. 2 is a rear view of part of the mechanism appearing in Fig. 1, showing the ratchet and pawl to better advantage, 0 while Fig. 3 is a view similar to Fig. 2 and showing a modification of the invention. 7

Referring to the drawing, the finger dial (not shown) has a central opening which fits over the slightly raised hub l3 on plate 12, being held 5 in place by a screw threaded in a hole at the center of I3. When the dial is in place, there fore, and is rotated in the usual manner, the member I2 will be rotated also, the direction of rotation being clockwise as seen in Fig. l, and 3 counter clockwise as seen in Fig. 2. The ratchet wheel l5 stands still while the member 12 is retated and consequently the pawl is, pivoted on l2 at H, will pass over the teeth of the ratchet wheel. The end of the pawl is held against the i ratchet wheel by a coil spring I 8, so that the pawl alternately rides up on ratchet teeth and drops into the succeeding notches. So far the construction is the same as disclosed in the patent referred to, and has the objection that a clicking noise is produced by the pawl as previ- 5 ously explained.

In order to eliminate this noise, there is provided according to the invention a spring l9, seen best in Fig. 1. One end of this spring is attached to the member 12 in any suitable manner, as by soldering, while the other end is bent over at right angles and is passed through the same hole in pawl 16 that accommodates the hook on the end of spring l8. This spring I9 is so tensioned that it begins to oppose the spring I8 after the pawl has dropped into a ratchet notch a short distance and arrests the further movement of the pawl by the time it has gone about half way into the notch, or at least before it reaches the bottom of the notch. 20

With this construction, as the pawl I6 is rotated around its movement relative to theratchet wheel is controlled by spring I8 and by spring l9 also, the first spring tending to force the pawl into the notches succeeding the ratchet teeth, and the latter spring stopping the movement of the pawl each time so that it never strikes the bottom of the notches. This entirely eliminates the clicking noise inherent in the ordinary pawl and ratchet. When the dial returns to normal and member I2 rotates back with it, the pawl I6 engages a tooth and rotates the ratchet wheel IS. The application of power through the pawl overcomes the tension of spring I9 and the pawl.

is drawn down into the notch to the full extent, thus securing normal engagement between pawl and ratchet during the impulse sending operation.

' Referring to Fig. 3, the modification there i1- lustrated will be explained. The member I2, 40 ratchet wheel l5, pawl l6, and spring 18', are the same as the correspondingly labeled parts in Fig. 2, except that the pawl 6 is shaped slightly difierent at the pivot end. At this end the pawl i6 is slotted and one end of a flat spring 20 is in- 5 serted under pressure, being thus secured to the pawl. The other end of spring 20 bears against a pin or stud 2i secured to member l2. With this arrangement it will be seen that when the pawl rides up on a ratchet tooth the spring 20 will move away from pin 2|, allowing a free movement of the pawl under control of spring 18'. When the pawl drops into the next notch under the tension of spring l8, the spring 20 moves toward pin 2| and reaches it after the pawl has passed a little way into the notch. The adjustment is such that movement of the pawl is arrested with the pawl about half way or a little more into the notch, as explained in connection with the first described form'of the invention. Since the pawl is prevented from dropping all the way into the successive notches on the ratchet wheel, the clicking noise is done away with.

The invention having been described, that which is believed to be new and for which the protection of Letters Patent is desired will be pointed out in the appended claims.

What is claimed is:

1. In a calling device having a dial and a ratchet and pawl mechanism operated thereby, means foreliminating noise during operation of the dial, said means comprising a spring adjusted to become effective each time'the pawl passes over a ratchet tooth and prevent the pawl from dropping to the bottom of the notch following such tooth. 2. In a calling device having a dial and a ratchet and pawl mechanism operated thereby, means for eliminating noise due to the pawl passing over successive ratchet teeth, said means comprising a spring which opposes the pawl open ating spring during movement of the pawl in the direction of the ratchet and limits the movement of the pawl.

3. In a ratchet and pawl mechanism for a calling device of the dial type in which the pawlis rotated .past successive teeth of the ratchet by operation of the dial, a spring for maintaining, the pawl pressed against the ratchet, and a second spring adjusted to oppose said first spring and stop movement of the pawl out of contact with the ratchet.

4. In a ratchet and pawl mechanism for a. calling device of the dial type in which the pawl is rotated past successive ratchet teeth by operation of the dial, a spring continuously under tension regardless of the position of the pawl and tending to hold it against the ratchet, and a second spring which is under tension only after the pawl has been moved a certain distance into a notch following a ratchet tooth, said second spring opposing said first spring to prevent the pawl from striking the bottom of the notch.-

5. In a calling device including a finger dial adapted for rotation against the tension of a spring, a ratchet wheel, a pawl rotated past successive ratchet teeth when the dial is rotated, a pawl spring for forcing the pawl into the notches between said ratchet teeth, and a third' spring which prevents the pawl from dropping to the bottom of said notches, said pawl and ratchet teeth being so designed that when said first spring applies power to the ratchet through the pawl the latter moves toward the ratchet against the tension of said third spring and fully engages a tooth of the ratchet.

6. In a calling device including a rotatable,

finger dial, a ratchet wheel, a. pawl adapted to'be rotated past and in contact with succlessive ratchet teeth when the dial is rotated, means for returning the dial, means for causingsaid pawl to engage a ratchet tooth at the beginning of the return movement, thereby rotating said ratchet wheel, and means for preventing click producing concussion between pawl and ratchet when the pawl slides over ratchet teeth on the,

SETH PETERSON. 

